Interlocking system for railroads



June 5, 1934. w. s. HENRY INTERLOCKING SYSTEM FOR RAILROADS Filed June 6, 1930 INVENT/OEQ BY w WATTORNEY Patented June 5, 1934 UNITE s'rArEs PATENT OFFICE William S. Henry, Goldwater, N. Y., assignor to General Railway Signal Company, Rochester,

Application June 6, 1930, Serial No. 459,443

7 Claims.

This invention relates to interlocking systems for railroads, and more particularly pertains to pole changer means for providing the reversibility of electric power operated switch machines used in such systems.

One object of the present invention is to provide series and shunt pole changer coils for operating and holding pole changer contacts to either of two extreme positions; these coils to be connected in such circuits that there will be practically no electro-static potential between the respective pairs of series and shunt coils. A further object of this invention is to permanently connect one side of the series and shunt coils to the particular terminal of the source oisupply which has the lowest insulation resistance in respect to earth.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawing and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference will be made to the single figure of the accompanying drawing which illustrates in a simplified and diagrammatic manner the parts and circuits of a well known type of an electric interlocking system employing dynamic indication and showing the organization of parts and circuits constituting the present invention.

For the purpose of more clearly illustrating the nature of this invention and facilitating in the explanation of the construction and mode of operation, there are shown in the accompanying drawing in a conventional manner the significant parts and circuits of an electric interlocking system of the dynamic indication type as disclosed in the patent to W. K. Howe, Patent No. 1,550,611 dated August 18, 1925, with the parts and circuits of the present invention applied thereto. It is to be understood that this specific type of interlocking system is merely illustrative of the nature and utility of the present invention, and that the invention may be applied to various other types of systems by making suitable changes in the mechanical and electrical details thereof.

With reference to the single figure of the accompanying drawing, a track switch TS is shown as operated by a switch machine SM of any suitable type, such for example, as shown in the patent to W. K. Howe, Patent No. 1,466,903 dated September 4, 1923, with the pole changer mechanism of such a switch machine constructed in accordance with the present invention. This switch machine SM includes the usual armature A and field winding F which cooperate to produce the driving torque for the switch machine. A group of pole changer contacts PC include movable contacts 5 and 6 which make contact between certain pairs of fixed contacts when in normal extreme positions and certain other pairs of fixed contacts when in reverse extreme positions. These movable contacts are mechanically operated by the switch machine to opposite positions in correspondence with the position of the track switch TS at the end of each operation; or, are electrically operated to opposite positions during the operation of the switch machine to thereby reverse the switch machine in mid-stroke. This electrical operation of the movable contacts 5 and 6 during the operation of the switch machine is provided for by a pole changer coil SE for operating the contacts to normal extreme positions and by a pole changer coil SH for operating the movable contacts to reverse extreme positions. A pole changer coil S is provided to hold the contacts 5 and 6 in normal positions, and a coil S is provided to hold the contacts 5 and 6 in reverse positions.

A group of pole changer coil contacts PCC includes movable contacts 7, 8, 9 and 10, which are capable of assuming normal positions, intermediate positions and reverse positions. These contacts are operated to intermediate positions as soon as the track switch TS is unlocked by the switch machine SM; and are operated to extreme positions in correspondence with the track switch as soon as the track switch is again locked. However, these contacts when operated to extreme positions, are preferably caused to be actuated slightly prior to the movement of the movable contacts 5 and 6 for reasons hereinafter pointed out. 7

The movable contact 7 makes contact between a pair of fixed contacts when in normal or intermediate positions, while the movable contact 8 makes contact between a pair of fixed contacts when in reverse or intermediate positions. The movable contact 9 makes contact between a pair of fixed contacts when in a normal position, while the movable contact 10 makes contact between a pair of fixed contacts when in a reverse position the contacts 9 and lO, when in an intermediate position, breaking contact.

The parts of the interlocking system located at the central tower or control office in general comprise a control lever L which is slidable back and forth to operate a tappet bar 11 by means of a cam slot 12 to accomplish the usual mechanical interlocking between the various control levers. The operation of this control lever L operates movable contact blocks 13 and 14 in a reciprocatory motion, which contact blocks make contact between their respective pairs of fixed contacts when in normal and half normal positions indicated by N and EN respectively, and certain other pairs of fixed contacts when in reverse and half reverse positions indicated by R and HR respectively. An indication latch mechanism for the lever L is designated by the reference character IL and has associated therewith an indication magnet 1M and a safety magnet S. Also, associated therewith is the usual cross protection polarized relay P, the usual indication selector IS with normal and reverse operating windings 15 and 16 for actuating movable contacts 1'7 and 18 to normal and reverse positions respectively, and abattery source of current supply designated BT.

With reference to the circuits of the accompanying drawing, it is obvious that the shunt coils SH and SH are directly connected to the negative terminal of battery ET through wire 20, fixed contact 21 of polarized relay P, movable contact 22 of polarized relay P, fixed contact 23 of polarized relay P, common return wire 24, then either through wire 25 to the shunt pole changer coil 81-1 or through wire 26 to the shunt pole changer coil SH.

Also, the series pole changer coils S and S are connected to the negative terminal of battery BT through wire 20, fixed contact 21, movable contact 22, fixed contact 23, wire 24, field winding F, wire 27, then either through wire 28 to the series pole changer coil 8, or wire 29 to the series pole changer coil S With the series and shunt pole changer coils thus connected to the same terminal of the source of supply, the electro static potential between the respective pairs of coils is substantially the same, which eliminates, while the system is at rest, continual stress upon the dielectric or insulating material separating the coils. Thus, the life of the insulation of the coils is considerably lengthened.

Although it is not the practice to connect the negative terminal of the source of supply of an interlocking system to ground or earth, as this would be undesirable, a condition, in effect somewhat similar to such a connection, exists due to the large number of contacts, terminals, coils and the like at each switch machine in the interlocking plant all of which are connected to the negative terminal of the battery through common return wires, which large number of contacts and the like are exposed to atmospheric conditions where dust and moisture collect forming a great number of high resistance leakage paths to ground. These leakage paths being in multiple, the resultant resistance from the negative terminal of the battery to ground is considerably reduced. However, such resultant resistance is still relatively high compared to the resistances of the actual circuits but in some instances may be as low, for example, as a thousand ohms.

By reference to the drawing, it may be noted that there are but two exposed contacts of the switch machine SM connected to the reverse operating wire 41 while there is a much larger number connected to the common return wire 24. This is representative of only one switch machine it being understood that all common return wires of all the switch machines are connected to the negative terminal of the battery in a similar manner. Thus, there is a smaller number of leakage paths from the positive terminal of the battery to ground than from the negative terminal to ground.

In consideration of the above, if coils are connected in the control wires respectively leading to the positive terminal of the battery, there may be an electro-static potential created between them and ground due to the resultant leakage path from the negative terminal of the battery BT to ground. In accordance with the present invention, such electro-static potential or stress upon insulation of the series coils S and S is eliminated, inasmuch as they are here connected to the negative, instead of the positive, terminal of the battery BT.

It is well known, that, where positive battery connections and negative battery connections are adjacent to each other and are covered with moisture and foreign particles as dust and dirt and the like, in a manner to form leakage paths, an electrolytic disintegration of the positive connection is carried on to a certain degree. By including the series pole changer coils on the negative side of the battery 31, such electrolytic disintegration of the coils is eliminated.

According to the present invention, the only time a series or a shunt pole changer coil is connected to the positive terminal or positive side of the battery ET is when the switch machine SM is in operation. This may be best explained by considering one typical operation of the system.

Operation-Let us assume that the lever L is moved from its present extreme normal position designated by the reference character N to the half reverse position designated by the reference character HR.

With the control lever L in a half reverse position, an initial operating circuit is completed from the positive terminal of the battery BT, through wire 85, windings of safety magnet S, wires 35 and 3'7, reverse winding 16 of indication selector IS, wire 38, contacts 39-14, wire 40, reverse operating wire 41, wire 42, contacts 43-5, wires 44 and 45, armature A, wire 46, contacts 4'76, wires 48 and 49, winding of series pole changer coil S, wires 28 and 27, field winding F, common return wire 24, fixed contact 23, movable contact 22, fixed contact 21, wire 20, to the negative terminal of the battery ET.

The current which flows in this initial operat- 1 ing circuit is not sufficient to operate the switch machine, but does actuate the movable contacts 17 and 18 of indication selector IS to reverse positions in which the reverse winding 16 is shunted out by movable contact 17 thereby completing the circuit from wire 36, through wire 50, movable contact 17, fixed contact 51, to wire 38 and thence through the circuit as heretofore traced. When the winding 16 is shunted out, the

switch machine armature A receives sufficient mediate position, while the opposite side of the coil is connected to the common return wire 24 through wire 25 as heretofore pointed out. Thus, this winding SH is connected in multiple with the field winding F, armature A and series coil S.

In a similar manner, the winding SI-I is connected in multiple with the switch machine when the movable contact 8 is in an intermediate or reverse extreme position. Thus, during the operation of the track switch, the energization of the opposite control wire, in this case the normal control wire 55, energizes the corresponding shunt coil, in this case coil SH provided lever L is normal, to operate the movable contacts 5 and 6 to opposite extreme positions to reverse the switch machine in mid-stroke.

While the switch machine is receiving current, the series pole changer coil S (for this reverse operation) is in series with the armature thereby checking the integrity of the circuit and the position of the pole changer contacts inasmuch as the switch machine could not operate if the coil were opened. In other words, as long as the switch machine receives current to operate, the contacts 5 and 6 must be held in proper positions to complete such an operation.

When the switch machine has operated the track switch TS to its reverse locked position, the movable contacts 7, 8, 9 and 10 are operated to reverse extreme positions slightly prior to the operation of the movable contacts 5 and 6 to corresponding reverse positions. The opening of contacts 54'7 deenergizes the shunt pole changer coil SH, while the closing of contacts 56--10 shunts out the series pole changer coil S thereby eliminating the magnetic pull or holding elTect exerted by these two coils upon the movable contacts 5 and 6 so that the mechanical operating means controlled by the switch machine may move these contacts 5 and 6 to reverse extreme positions without undue stresses.

The circuit shunting out the series pole changer coil S with the track switch locked in a reverse position is traced from its left hand terminal, through wires 49 and 60, contacts 56-10, wires 61 and 62 to the right terminal of the coil.

As soon as the movable contacts 5 and 6 assume extreme reverse positions, a dynamic indication circuit is completed. Current flows in this indication circuit due to the free run of the armature A and energizes the indication magnet IM thereby releasing the indication latch IL to permit the operator to move the control lever L to a full reverse position indicated by the reference character R.

The reverse indication circuit is completed from the upper terminal of the armature A, through wires 46 and 63, contacts 645, wire 65, normal operating wire 55, wire 66, contacts 6'713, wire 68, fixed contact 69, movable contact 18 in a reverse position, wire 70, windings of indication magnet IM, wire 71, :winding of polarized cross protection relay P, wire 72, fixed contact 73, movable contact 22, fixed contact 23, common return wire 24, field winding F, wires 27 and 29, series coil S wires '74 and 75, contacts 766, wire 45, to the lower terminal of armature A.

The operation of the system causing the switch machine SM to return the track switch TS to a full normal locked position as shown, will not be explained in detail as it can be understood by analogy to the operation already explained.

It is noted however, that, when the switch machine has operated the track switch TS to a normal locked position, the series pole changer coil S is shunted by a circuit from its left hand terminal, through wires 74 and '77, contacts 78-9, wires 62, 28 and 29, to the right hand terminal of the coil, slightly prior to the opening of the normal operating circuit. Also, the normal dynamic indication circuit is completed from the lower terminal of the armature A, through wires 45 and 44, contacts 43--5, wire 42, reverse operating wire 41, contacts 89-13, wire 81, fixed contact 82, movable contact 18, wire '70, windings of indication magnet IM, wire 71, winding of polarized cross-protection relay P, wire 72, fixed contact 73, movable contact 22, fixed contact 23, common return wire 24, field winding F, wires 27 and 28, series coil S wires 49 and 48, contacts 47-6, wire 46, to the upper terminal of armature A.

Thus, during the time that the system is at rest either in normal or reverse conditions, the series coils S are both shunted, one through a local circuit in the pole changer mechanism and the other through the dynamic indication circuit.

It is to be understood that the various features attributed to a dynamic indication interlocking system such as set forth in the above mentioned Patent No. 1,550,611 are included as characteristic of this system although they have not been specifically mentioned, it being understood that the features of this invention pertain more particularly to the pole changing mechanism and circuit arrangementemployed with the switch machine.

Although one specific construction of devices and arrangement of circuits, designed for use in connection with one particular type of electric interlocking system, has been selected for the disclosure of the nature and scope of the present invention, it will be evident that various modifications and adaptations of this specific embodiment shown and described may be made in practice Without departing from the invention.

What I claim is:

1. In an interlocking system for railroads, a switch machine of the electric power driven type having field and armature windings, a source of electrical energy having positive and negative terminals, a pole changer mechanism having contacts capable of assuming either of two extreme positions and having a holding coil for each extreme position, means connecting one of said holding coils in series with said field and armature windings with said pole changer contacts in one extreme position said means connecting the other one of said holding coils in series with said field and armature windings with said pole changer contacts in the other extreme position, and means permanently connecting said holding coils, under normal conditions to said negative terminal of said source, whereby electrolytic action cannot occur in a manner to disintegrate said holding coils.

2. In combination, a switch machine having normal and reverse operating circuits, a pole changer mechanism having holding coils and operating coils, said holding coils being energized respectively in series with said switch machine and said operating coils being energized respectively in multiple with said switch machine, a battery source having positive and negative terminals, and means permanently connecting said holding and said operating coils to the particular terminal of said battery source having a potential nearer ground potential.

3. In combination, a switch machine having normal and reverse operating circuits, a pole changer mechanism having holding coils and operating coils, said holding coils being energized respectively in series with said switch machine and said operating coils being energized respectively in multiple with said switch machine, a battery source having positive and negative terminals, and means permanently connecting said holding coils and said operating coils to the negative terminal of said battery source, whereby electrolytic action cannot occur in a manner to disintegrate said holding coils and said operating coils.

i. In combination, a motor having field and armature windings, a pole changer mechanism having a plurality of contacts capable of assuming either of two extreme positions, a pair of holding coils for each extreme position of said movable contacts, means energizing the particular pair of said holding coils corresponding to the last operated position of said movable contacts upon the next operation of said motor, one of said coils of such pair being connected in multiple with said field and armature windings, the other of said holding coils of such pair being connected in series with said field and armature windings, and means permanently interconnecting all of said holding coils, whereby all of said coils are at substantially the same electro-static potential.

5. In an interlocking system for railroads, a switch machine having normal and reverse operating circuits, a circuit controller adapted to alternately control the current supply of said operating circuits, pole changer contacts operated by said switch machine to either of two extreme positions, a pair of holding coils for each extreme position of said pole changer contacts, means energizing the particular pair of said holding coils corresponding to the last operated position of said pole changer contacts upon the energization of the next operating circuit, said means energizing one holding coil of said pair in multiple with said switch machine and energizing the other coil of said pair in series with said switch machine, and means deenergizing said particular pair of holding coils at the end of each operation prior to the deenergization of said next operating circuit.

6. In combination, a switch machine having armature and field windings, normal and reverse operating wires in conjunction with a common return wire, a source of electrical energy, means connecting one terminal of said source to said common return wire, a manually operable circuit controller adapted to connect the other terminal of said source to either said normal or said reverse operating wire, pole changer contacts operated to either of two extreme positions by said switch machine at the end of each operation, a holding coil for each extreme position of said pole changer contacts, means connecting one side or" said holding coil to one side of said field winding, means connecting the other side of said field winding to said common return wire, means including said pole changer contacts for connecting the other side of the particular one of said holding coils corresponding to the last operated position of said pole changer contacts to one side of said armature, and means including said pole changer contacts for connecting the other side of said armature to the particular operating wire next to be energized.

7. In combination, a switch machine having normal and reverse operating circuits, a pole changer mechanism having holding coils and operating coils, said holding coils being energized respectively in series with said switch machine and said op rating coils being energized respectively in multiple with said switch machine, a battery source having positive and negative terminals, and means unaffected by the operation of said switch machine for connecting said holding coils and said operating coils to the particular terminal of said battery source having a potential near ground potential.

WILLIAM S. HENRY. 

